The invention relates to a washing machine and more particularly to an improved washing tub.
Conventional washing machines generally accomplish washing action by establishing a vortex flow within a washing tub to repeatedly agitate the clothes being washed. In such a machine, it is required to utilize a rather large tub capacity when compared to the amount of clothes being washed. In the case where a small load of clothes is desired to be washed, the vortex flow is so vigorous that the clothes are excessively washed, and may be damaged. On the other hand, if a large amount of clothes are washed, the vortex flow becomes too slow and the clothes are not washed enough.
Moreover, since the clothes only accidently contact the agitator of the washing machine, one may not expect that all of the clothes are washed enough by the twisting effect of the agitator within the washing tub. Conversely, the clothes which do contact the agitator frequently, are washed excessively, so that some articles being washed are damaged within the washing tub.
Recently, a new type of washing machine is available. This type of washing machine, does not have an agitator, but does have a washing tub which is horizontally rotatable with the washing liquid and clothes placed therein. The tub is intermittently rotated in forward and reverse directions to wash the clothes through a vortex flow and the difference in rotational speed between the washing liquid and clothes.
In such an apparatus, the clothes are not damaged. Examples of such washing machines are shown in Japanese patent publications Nos. 51-56580, 49-33863, and U.S. Pat. No. 2,986,916. Other examples of related art include Japanese patent disclosures Nos. 36-13469 and 55-25878. However, in this type of washing machine the washing efficiency is poor, because the difference in the rotational speed of the liquid and clothes is small. Accordingly, such conventional washing machines fail to wash clothes in a homogeneous manner, particularly when the washing load varies from small to large.